Answer:
x = 3
y = 2
Step-by-step explanation:
4x + 3(3x - 7) = 18 <em>Substitute</em><em> </em><em>y</em>
4x + 9x - 21 = 18 <em>Simply</em>
13x - 21 = 18 <em>Add</em><em> </em><em>like</em><em> </em><em>terms</em>
13x = 39 <em>Add</em><em> </em><em>2</em><em>1</em>
x = 3 <em>Divide</em><em> </em><em>by</em><em> </em><em>1</em><em>3</em>
y = 3(3) - 7 <em>Substitute</em><em> </em><em>x</em>
y = 9 - 7 <em>Simply</em>
y = 2 <em>Subtract</em>
Let's check:
4(3) + 3(2) = 18
12 + 6 = 18
18 = 18
It works!
Answer:
2.375 or 2 3/8
Step-by-step explanation:
You want to do total weight over total number of items.
14 1/4 / 6 books = 2.375
Answer:
2,655 students
Step-by-step explanation:
The z-score for a 99% confidence interval is z = 2.576
The standard error for a proportion p is:
For a proportion of p =0.20, in order to ensure a standard error of 0.02, the sample size 'n' must be:
Rounding up to the next whole student, the sample size needed is 2,655 students.
Round off the decimals to a sensible number.
So 3.7 would be 4 and 10.2 would be 10.
In this case, it would be (2 × 4 + 8) × 10 which is 160.
